Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

From January 2018 to December 2024, 75% of Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%).

  • Total suspected cases: 39,248
  • Total confirmed cases: 5,948
  • Deaths from Confirmed Cases: 1,089
  • Case Fatality Ratio: 20%
  • Number of Health Care Workers: 231

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all lab confirmed cases in Nigeria was between 16-27% and decreased over time.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • The variation in CFR is likely due to late patient presentation and differences in case management, highlighting the need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 11

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 3,226 suspected cases were reported from 1 in Niger, Akwa Ibom, Jigawa, Katsina, Kwara to 1,011 in Edo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 32% decrease in the cumulative number of suspected cases reported.

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 21% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 11, 87% of LF cases are from Ondo (30%), Bauchi (24%), Edo (17%), and Taraba (16%) States.

  • Total confirmed cases: 604

  • Deaths from Confirmed Cases: 113

  • Case Fatality Ratio: 19%

  • Number of Health Care Workers: 19

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 11 2025, cumulatively 604 cases and 113 deaths (CFR=19%) across 16 States have been reported.
  • At same period 2024, a total of 27 States reported at least one confirmed cases.
  • There is a 32% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • There is a 21% decrease in the number of confirmed cases reported in 2025 compared to 2024.
  • In 2024,
    • 35 States had reported at least one suspected case versus 33 States in 2025 to date.
    • 27 States had reported at least one confirmed case versus 16 States in 2025 to date.

Health care worker infections 2020-2025 epiweek 11


  • Top 5 states:
    • 8 HCW infections in Ondo
    • 4 HCW infections in Bauchi
    • 2 HCW infections in Taraba
    • 2 HCW infections in Gombe
    • 1 HCW infections in Ebonyi.

  • As of epi week 11 of 2025, there has been 19 healthcare workers infected, that is 3% of confirmed cases.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 11)

Lassa fever in Ondo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ondo as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 874 183 22 12%
2024 968 176 13 7%
2023 971 249 30 12%
2022 575 190 33 17%
2021 231 59 16 27%
2020 417 294 40 14%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ondo State reported 183 confirmed cases including 22 deaths (CFR 12%).
  • Compared to same period 2024, this represents:
    • 10% decrease in the number of suspected cases.
    • 4% increase in the number of confirmed cases.
    • 63% increase in CFR.




  • In 2024 as of week 11:
    • 968 in the number of suspected cases.
    • 176 in the number of confirmed cases.
    • 13 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 11:
    • 971 in the number of suspected cases.
    • 249 in the number of confirmed cases.
    • 30 in the number of deaths.
    • 12% average CFR.




  • In 2022 as of week 11:
    • 575 in the number of suspected cases.
    • 190 in the number of confirmed cases.
    • 33 in the number of deaths.
    • 17% average CFR.




  • In 2021 as of week 11:
    • 231 in the number of suspected cases.
    • 59 in the number of confirmed cases.
    • 16 in the number of deaths.
    • 27% average CFR.




  • In 2020 as of week 11:
    • 417 in the number of suspected cases.
    • 294 in the number of confirmed cases.
    • 40 in the number of deaths.
    • 14% average CFR.

Lassa fever in Bauchi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Bauchi as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 618 147 12 8%
2024 530 120 26 22%
2023 551 78 14 18%
2022 550 98 10 10%
2021 34 7 2 29%
2020 205 39 15 38%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Bauchi State reported 147 confirmed cases including 12 deaths (CFR 8%).
  • Compared to same period 2024, this represents:
    • 17% increase in the number of suspected cases.
    • 22% increase in the number of confirmed cases.
    • 62% decrease in CFR.




  • In 2024 as of week 11:
    • 530 in the number of suspected cases.
    • 120 in the number of confirmed cases.
    • 26 in the number of deaths.
    • 22% average CFR.




  • In 2023 as of week 11:
    • 551 in the number of suspected cases.
    • 78 in the number of confirmed cases.
    • 14 in the number of deaths.
    • 18% average CFR.




  • In 2022 as of week 11:
    • 550 in the number of suspected cases.
    • 98 in the number of confirmed cases.
    • 10 in the number of deaths.
    • 10% average CFR.




  • In 2021 as of week 11:
    • 34 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.




  • In 2020 as of week 11:
    • 205 in the number of suspected cases.
    • 39 in the number of confirmed cases.
    • 15 in the number of deaths.
    • 38% average CFR.

Lassa fever in Edo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Edo as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 1011 102 15 15%
2024 1101 174 23 13%
2023 1314 231 30 13%
2022 1008 158 21 13%
2021 797 97 11 11%
2020 872 299 33 11%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Edo State reported 102 confirmed cases including 15 deaths (CFR 15%).
  • Compared to same period 2024, this represents:
    • 8% decrease in the number of suspected cases.
    • 41% decrease in the number of confirmed cases.
    • 11% increase in CFR.




  • In 2024 as of week 11:
    • 1101 in the number of suspected cases.
    • 174 in the number of confirmed cases.
    • 23 in the number of deaths.
    • 13% average CFR.




  • In 2023 as of week 11:
    • 1314 in the number of suspected cases.
    • 231 in the number of confirmed cases.
    • 30 in the number of deaths.
    • 13% average CFR.




  • In 2022 as of week 11:
    • 1008 in the number of suspected cases.
    • 158 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 13% average CFR.




  • In 2021 as of week 11:
    • 797 in the number of suspected cases.
    • 97 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 11% average CFR.




  • In 2020 as of week 11:
    • 872 in the number of suspected cases.
    • 299 in the number of confirmed cases.
    • 33 in the number of deaths.
    • 11% average CFR.

Lassa fever in Taraba State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Taraba as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 228 96 30 31%
2024 163 90 19 21%
2023 198 70 25 36%
2022 61 28 14 50%
2021 46 18 11 61%
2020 77 52 21 40%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Taraba State reported 96 confirmed cases including 30 deaths (CFR 31%).
  • Compared to same period 2024, this represents:
    • 40% increase in the number of suspected cases.
    • 7% increase in the number of confirmed cases.
    • 48% increase in CFR.




  • In 2024 as of week 11:
    • 163 in the number of suspected cases.
    • 90 in the number of confirmed cases.
    • 19 in the number of deaths.
    • 21% average CFR.




  • In 2023 as of week 11:
    • 198 in the number of suspected cases.
    • 70 in the number of confirmed cases.
    • 25 in the number of deaths.
    • 36% average CFR.




  • In 2022 as of week 11:
    • 61 in the number of suspected cases.
    • 28 in the number of confirmed cases.
    • 14 in the number of deaths.
    • 50% average CFR.




  • In 2021 as of week 11:
    • 46 in the number of suspected cases.
    • 18 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 61% average CFR.




  • In 2020 as of week 11:
    • 77 in the number of suspected cases.
    • 52 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 40% average CFR.

Lassa fever in Ebonyi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ebonyi as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 92 19 9 47%
2024 196 43 24 56%
2023 147 49 27 55%
2022 167 35 15 43%
2021 72 15 6 40%
2020 137 67 16 24%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ebonyi State reported 19 confirmed cases including 9 deaths (CFR 47%).
  • Compared to same period 2024, this represents:
    • 53% decrease in the number of suspected cases.
    • 56% decrease in the number of confirmed cases.
    • 15% decrease in CFR.




  • In 2024 as of week 11:
    • 196 in the number of suspected cases.
    • 43 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 56% average CFR.




  • In 2023 as of week 11:
    • 147 in the number of suspected cases.
    • 49 in the number of confirmed cases.
    • 27 in the number of deaths.
    • 55% average CFR.




  • In 2022 as of week 11:
    • 167 in the number of suspected cases.
    • 35 in the number of confirmed cases.
    • 15 in the number of deaths.
    • 43% average CFR.




  • In 2021 as of week 11:
    • 72 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2020 as of week 11:
    • 137 in the number of suspected cases.
    • 67 in the number of confirmed cases.
    • 16 in the number of deaths.
    • 24% average CFR.

Lassa fever in Kogi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Kogi as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 63 15 4 27%
2024 92 27 1 4%
2023 30 10 1 10%
2022 88 32 6 19%
2021 5 1 0 0%
2020 68 31 8 26%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Kogi State reported 15 confirmed cases including 4 deaths (CFR 27%).
  • Compared to same period 2024, this represents:
    • 32% decrease in the number of suspected cases.
    • 44% decrease in the number of confirmed cases.
    • 620% increase in CFR.




  • In 2024 as of week 11:
    • 92 in the number of suspected cases.
    • 27 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 4% average CFR.




  • In 2023 as of week 11:
    • 30 in the number of suspected cases.
    • 10 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 10% average CFR.




  • In 2022 as of week 11:
    • 88 in the number of suspected cases.
    • 32 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 19% average CFR.




  • In 2021 as of week 11:
    • 5 in the number of suspected cases.
    • 1 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 11:
    • 68 in the number of suspected cases.
    • 31 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 26% average CFR.

Lassa fever in Gombe State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 50 11 6 55%
2024 25 3 1 33%
2023 26 6 0 0%
2022 96 15 6 40%
2021 2 0 0 –
2020 19 6 1 17%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 11 confirmed cases including 6 deaths (CFR 55%).
  • Compared to same period 2024, this represents:
    • 100% increase in the number of suspected cases.
    • 267% increase in the number of confirmed cases.
    • 64% increase in CFR.




  • In 2024 as of week 11:
    • 25 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 33% average CFR.




  • In 2023 as of week 11:
    • 26 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2022 as of week 11:
    • 96 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2021 as of week 11:
    • 2 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 11:
    • 19 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 17% average CFR.

Lassa fever in Benue State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Benue as of week 11:
Years Suspected cases Confirmed cases Deaths CFR
2025 27 5 3 60%
2024 970 60 9 15%
2023 110 36 3 8%
2022 183 30 8 27%
2021 13 3 0 0%
2020 20 7 2 29%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Benue State reported 5 confirmed cases including 3 deaths (CFR 60%).
  • Compared to same period 2024, this represents:
    • 97% decrease in the number of suspected cases.
    • 92% decrease in the number of confirmed cases.
    • 300% increase in CFR.




  • In 2024 as of week 11:
    • 970 in the number of suspected cases.
    • 60 in the number of confirmed cases.
    • 9 in the number of deaths.
    • 15% average CFR.




  • In 2023 as of week 11:
    • 110 in the number of suspected cases.
    • 36 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 8% average CFR.




  • In 2022 as of week 11:
    • 183 in the number of suspected cases.
    • 30 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 27% average CFR.




  • In 2021 as of week 11:
    • 13 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 11:
    • 20 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.

Thank you

Any questions or suggestions? Contact us: Anaïs Legand and Antoine Chaillon